Commit cc4816bd authored by David Yang's avatar David Yang Committed by Paolo Abeni
Browse files

net: openvswitch: fix data race in ovs_vport_get_upcall_stats 



In ovs_vport_get_upcall_stats(), some statistics protected by
u64_stats_sync, are read and accumulated in ignorance of possible
u64_stats_fetch_retry() events. These statistics are already accumulated
by u64_stats_inc(). Fix this by reading them into temporary variables
first.

Fixes: 1933ea36 ("net: openvswitch: Add support to count upcall packets")
Signed-off-by: default avatarDavid Yang <mmyangfl@gmail.com>
Acked-by: default avatarIlya Maximets <i.maximets@ovn.org>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarAaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20260121072932.2360971-1-mmyangfl@gmail.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 19e4175e

net/openvswitch/vport.c

+6 −5
Original line number Diff line number Diff line
@@ -310,22 +310,23 @@ void ovs_vport_get_stats(struct vport *vport, struct ovs_vport_stats *stats) 
 */

int ovs_vport_get_upcall_stats(struct vport *vport, struct sk_buff *skb)

{

	u64 tx_success = 0, tx_fail = 0;

	struct nlattr *nla;

	int i;



	__u64 tx_success = 0;

	__u64 tx_fail = 0;



	for_each_possible_cpu(i) {

		const struct vport_upcall_stats_percpu *stats;

		u64 n_success, n_fail;

		unsigned int start;



		stats = per_cpu_ptr(vport->upcall_stats, i);

		do {

			start = u64_stats_fetch_begin(&stats->syncp);

			tx_success += u64_stats_read(&stats->n_success);

			tx_fail += u64_stats_read(&stats->n_fail);

			n_success = u64_stats_read(&stats->n_success);

			n_fail = u64_stats_read(&stats->n_fail);

		} while (u64_stats_fetch_retry(&stats->syncp, start));

		tx_success += n_success;

		tx_fail += n_fail;

	}



	nla = nla_nest_start_noflag(skb, OVS_VPORT_ATTR_UPCALL_STATS);